Modulating gas burner



Jan. 20, 1953 v. s. BECK 2,626,105

MQDULATING GAS BURNER Original Fifled June 30, i949 2 SHEETS-SHEET l v. s. EcK

MODULATING GAS BURNER Jan. 20, 1953 2' SHEETSSHEET 2 Original Filed June 30, 1949 FIG.

5k 4 5\ A W fl J m 2 a c l 9 W m 7 f t Z n 0 w M m ru 65 7 Control for 5 FIG 8 'quence of starting of the burner groups.

Patented Jan. 20, 1953 MODULATING GAS BURNER Vernon S. Beck, St. Louis, Mo.

Original application June 30, 1949, Serial No. 102,370. Divided and this application January 17, 1951, Serial No. 206,438. In Canada June 6 Claims.

This invention relates to gas burners of the modulating variety for heating and power systems.

This application is a division of my copending application Serial No. 102,370, filed June 30, 1949, for Modulating Gas Burner, which contains claims to the burner unit shown but not claimed herein.

needed for satisfying normal heating requirements under varying conditions of heat loss from the region being heated. A thermostat responsive to a desired air temperature, through a sequence relay circuit collectively controls the se- Thus only a sufficient number of burner groups is in operation at any one time, operating at best efficiency to supply the existent heating load; and in addition, when it is necessary to .bring more than one group of burners into operation, the respective groups are sequentially introduced so as to eliminate the concussion which ordinarily occurs when all of the burners of a furnace of substantial size are ignited at once. Thus the invention results in automatically obtaining higher operating efficiencies under all load conditions from a unit of the type described. It also results in a much quieter modulated control for bringing burners into operation. Other features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, steps and sequence of steps, features of construction and arrangements of parts which will .be exemplifled in the structures and methods hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a front end view of a gas burner unit embodying my invention;

Fig. 2 is a cross section viewed on lines 2-2.of

.Figs. 1 and 3;

Fig. 3 is a horizontal section taken on line 3-3 of Fig. 2;

Fi 4 is a vertical section taken on line 4-4 of Fig. 2;

Fig. 5 is a plan view of Fig. 2 but showing certain burner heads removed;

Fig. 6 is a fragmentary detail plan view 0 several burner heads;

Fig. '7 is a vertical section taken on line 'l--| of Fig. 6; and.

Fig. 8 is a wiring diagram.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

While the present invention is described for burners in an insertable unit used in connection with steam heating boilers, it will be understood that the invention is useful for hot water boilers and also for warm air heating furnaces.

In most prior heatin systems employing gas burners, all burners were brought into action at the same time, which caused a considerable concusion and vibration as all of the burners became lighted, particularly in cases of large capacity burners. One solution to the problem has been the provision of slow-opening supply valves.

These supplied all burners at once and were used for controlling the volume of gas not only for starting but modulating for load requirements. In the latter connection, such valves were unsatisfactory because the range of change in control was extremely limited. For example, by reducing gas pressure from four ounces to one ounce (an extreme for most burners) a reduction of capacity of only 50% can be attained, which under many circumstances results in waste. In some cases sequentially ignited groups of burners have been employed with air supplies which were individual to the groups, but these were not built into units for convenient application to various furnaces and required a substantial amount of special installation work. By means of the present invention, a convenient unit is provided having the ability to be applied to and match various load requirements of any of -a wide variety of heating plants. Moreover, the present invention may be used either without or in conjunction with slow-acting valves, thereby extending its field .of usefulness.

Referring now more particularly to Figs. 1 5,

there is shown at numeral 1 an enclosed rectangular base which forms an air box unit plenum chambers 9, II and I3, which receive air through forward control doors l5, I1 and I9, respectively. The top 3is provided with longitudinal outlet slots 2| for issuance of secondary air. Each slot 2| traverses all of the plenum chambers 9, H and I3. Thus a part of each slot 2| forms an outlet for secondary air from one of the plenum chambers. Between the slots 2| in the top 3 are located openings 23 for the reception of burner assemblies 25. The character of each burner assembly is shown in Figs. 6 and 7, and comprises a top manifold 21 having outlets 29 with passages 3| for rising secondary air. Each manifold 21 is on the top of a mixing pipe 33 having a Venturi inlet 35. This inlet is adapted to receive gas from nozzles 31 and also primary air which sweeps into the venturi with the gas from these nozzles. The burner assemblies 25 are removable and interchangeable with respect to the openings 23. The entirenumberof burners 25 may be considered to be sectionalized according to the groups associated plenum chambers "9, II and l3, into which their lower ends extend.

Thus (Fig.2), all of the air for the section A of burners is supplied through the plenum chambet 9; all of that for section B through the plenum chamber H; and all for section C through the plenum chamber l3. One advantage of this construction is that no group of burners becomes starved of air, since all of the air cannot shortcircuit through any one group of burners.

The gas supply for the burner groups is also sectionalized. This is done by sectionalizing the nozzles 31 into groups a, b and c, The group a of nozzles 31 is located in branched manifold pipes 39, extending from a lateral header 4| supplied by an inside leader 43'. The group b of nozzles 31 is located in branched manifold pipes 45, extending from'a lateral header 4! supplied by an inside leader 49. nozzles 31 is located in branched manifold pipes extending from a lateral header 53 supplied by an inside leader 55. All of the leader pipes 43, 49 and 55 are supplied from a main gas line 51 to which they may be conveniently attached. As shown in Fig. 5, a pilot line 59 from the main supplies two pilot burners 5| for the section A;

pilot line 63 supplies two pilot burners 95 for the section B; and a pilot line 61 supplies two pilot burners 69 for the section C. This'arrangement allows for convenient insertion of the headers 4|,

41 and 53 and manifold pipes 39, 45 and 5| in the respective plenum chambers 9, I and I3 and convenient application of the burner heads above these chambers. Grouping of the heads is automatic, even when applied indiscriminately.

In the pipes 43, 49 and 55 are manual shutoif cocks II and suitable presure regulators 13; also electrically operated gas valves 15, 11 and 19, respectively. These valves 15, TI, 19 are under control of boiler-pressure-operated switches 8|, 83and 85, (see Fig. 8). The switches 8|, 83 and 85 are opened and closed in response to predetermined thermal conditions or pressures of the medium that the burners heat. Thus for example, when the boiler ste am pressure drops to a small differential under 5 p. s. i., switch 8| will close, thus energizing valve to open; when it drops to a small differential under 4% p. s. i., switch 83 will close and energize valve 11 to open; and when it drops to a small differential under 4 p. s. i., switch 85 will close and energize valve 19 to open. When one of the switches 8|, 83 or 85 closes, it energizes'the respective gas valve I5, I 11 orl'9 which opens promptly, although these" The group 0 of 1 valves may be of the slow opening type if desired. In conventional gas fired systems any gas valve control used for controlling a set of burners is commonly arranged to shut off the air damper door for such burners when the gas valve is closed, so as to prevent undue cooling of the heating surfaces between firings. That practice is followed in the present construction so that door l5 closes when valve 15 is closed; door I! closes when valve 11 is closed; and door l9 closes when valve I9 closes. Means for this purpose being common and of a wide variety of forms, further details are unnecessary.

A typical wiring diagram is shown in Fig. 8, in which 8'! indicates a thermostat in a main line or trunk circuit 89. It is by means of this thermostat 81 that calls are made automatically for heat. When the thermostat 8'! is satisfied, the circuit 89 is broken; otherwise it is closed. Circuit 89 serves another trunk circuit through a transformer |0|. This circuit 99 supplies a branch circuit 9|, which includes the pressure controlled switch 8| and electrically operated gas valve 15 controlling section A and also the motoring elements of a time delay switch 93. Thus if the circuit 9| has been prepared by previous closing of the pressure switch 8|, valve 15 for section A will open when the thermostat 81 closes in response to a predetermined reduction in temperature in the space or medium being heated by the steam system. This also energizes the time switch 93 which, after a suitable interval, closes in a branch circuit 95. This circuit 95, if previously prepared by closing of pressure switch 83, energizes gas valve H to open in section B. Thus section B will come into operation automatically a predetermined short interval after section A comes into operation, provided section B has been prepared.

The circuit also energizes a branch circuit 96, which energizes the motoring elements of a second time delay switch 91, serving to close in a control circuit 99. Therefore the circuit 99, if prepared by the pressure-controlled switch 85, causes valve 19 to open a suitable interval of time after valve 11 has opened.

In the circuit 9! are pilot safety switches I03, which are closed as long as pilots 6| are burning; in the circuit 95 are pilot control switches I05 which are closed as long as the pilots 65 are burning; and in the circuit 99 are pilot control switches l0! which are closed as longas the pilots 59 are burning.

It will be observed that the thermostatic control 8'! collectively controls the branch circuits 90, 95 and 95, each of which individually controls the fuel supplied to a burner group.

Operation is as follows:

Assume that all pilot lights GI, 65 and 69 are burning and that thermostat 8'! calls for heat, thus closing circuit 89 and energizing circuit 90.

If upon a call by the thermostat 81 the pressure is under a suitable differential below 4 p. s. i., all of the pressure-controlled switches BI, 83 and 85 have prepared their circuits 9|, 95 and 99, respectively. Valve 15 for section A opens immediately, thus lighting section A. Since time switch 93 is energized, it energizes circuit 95 after a suitable interval, at which time the prepared circuit 95 is energized and valve 1! opened, thus lighting section B. This also energizes the time switch 91, which after a suitable interval energizes the prepared circuit 99, thus opening stat 81 is under pressure conditions above a small increment over 4 /2 p. s. i., circuit 99 will not be prepared by any closure of the pressure-controlled valve' 85; Hence valve 19 will never open. This means that the heating load under the prevailing conditionsv can be supplied without all burners being in operation and it is taken care of by lighting of sections A and: B in sequence.

In the event that the call made by the thermostat 81 is under pressure conditions above a small increment over 4% p. s. i., circuit 95 also will not be prepared by any closure of the pressure-controlled switch 83. Hence valve 11 will never open. This means that the heating load under the prevailing conditions can be supplied by operation of section A only.

When the thermostat Bl ceases to call for heat, all circuits become deenergized and all of the valves 15, 11 and 19 close, thus turning off all burners at the same time. Since no condition of concussion or vibration is associated with turning all burners oil at once, no sequential operation is used in this connection.

Thus it will be seen that a double modulation control is obtained. First, the burner sections light in sequence, regardless of how many sections are required to carry the load. Second, only such a number of sections is called upon to light as are required to carry the load. Moreover, each section when lighted receives its independent supply of primary and secondary air, unaffected by the requirements of any other section. The result is that the burners operate to start quietly and to supply the load efficiently under all conditions.

It will be appreciated that the devices 8|, 83 and 85 are responsive to boiler temperature conditions inasmuch as there is a correlation between steam pressure and steam temperature.

It may be noted that the air box I is installed with the air inlets I5, l1, I9 located at the front end of the boiler served, that is, the end farthest from the flue connection. Thus when less than all of the burner groups are ignited practically all of the boiler heating surfaces are reached by the resulting hot gases. It is also clear from the drawings that the box I with the contained and attached parts is in its construction independent of any furnace walls or settings, being in the form of a self-contained unit which may be factory-assembled and shipped for simple insertion in any of various furnaces.

It is to be understood that, although the invention has been described as built for a triplegrouped arrangement, it also may be built for other group multiples, such as two, four, five et cetera.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions and methods without departing from :the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

'1. In a steam heating system having a boiler heated by a plurality of burner groups, the heated steam being adapted to heat a space that is to be maintained at a predetermined temperature, individual electrically controlled fuel valves for each burner group, a control circuit for said electrically controlled valves comprising a plurality of branch circuits each controlling one 01 said valves, a pressure-responsive control switch in each branch circuit, each pressure-responsive switch being closed at a difierent value of boiler pressure, a thermostatic switch connected in series with all of said branch circuits, said thermostatic switch being responsive to-the temperature of the space to be heated, and time-delay switches sequentially responsive to closure of the thermostatic switch and series connected with said pressure-responsive switches.

2. For a heating system of the type having a furnace, a heat-transfer medium heated at the furnace and space-heating means remote from the furnace supplied by said heat-transfer medium; a control system comprising at least two burners inthe furnace, a thermostatic control device located in the space supplied by said spaceheating means for collectively controlling the burners, a second temperature-responsive burner control device located in connection with the furnace and responsive to the temperature of said heat-transfer medium, said second burner control device controlling one of the burners and being effective to operate said burner only when the temperature of the heat-transfer medium is below a predetermined value, and time-delay means responsive to operation of said thermostatic control for preventing operation of the other burner for a predetermined time after the thermostatic control has initiated operation of said one burner.

3. For a heating system of the type having a boiler, a steam system and a space remote from the boiler adapted to be heated by steam; a control system comprising at least two burners for heating the boiler, a thermostatic control located in said space collectively controlling operation of the burners, a pressure-responsive burner control in communication with the boiler, said second burner control being effective to operate one of said burners only when the boiler pressure is below a predetermined value, and time-delay means responsive to operation of said thermostatic control for preventing the second burner control from becoming effective for a predetermined time after operation of said thermostatic control.

4. A control as set forth in claim 3 wherein each burner has a solenoid valve, branch circuits for operating said valves, a thermostatic switch series connected with both branch circuits, a time-delay switch energized upon closure of the thermostatic switch connected in one branch circuit, and a pressure-responsive switch connected in said one branch circuit.

5. A control system for a furnace having first and second burners and supplying a heat-transfer medium to a space to be heated, the latter containing a main control thermostat; comprising a first circuit, means therein adapted to prepare the circuit for starting the first burner in response to a predetermined first decrement of temperature in the heating medium, said thermostat being adapted upon a predetermined decrement of space temperature to energize the circuit if prepared and to start the first burner, and a second circuit, means in said second circuit adapted to prepare it for starting the second burner in response to a further decrement of temperature in the heating medium, means operative from said first circuit with time delay for energizing said second circuit when said first circuit is energized and when said second circuit is prepared.

6. A control system for a furnace having first,

second and third burners and supplying a heattransfer medium to a space to be heated, the latter containing a main control thermostat; comprising a first circuit, switch means therein adapted to prepare the circuit for starting the first burner in response to a predetermined first decrement of temperature in the heating medium, said thermostat being adapted upon a predetermined decrement of space temperature to energize the first circuit if prepared and to start therfirst burner, a second circuit connected for operation with time delay from the first circuit when the latter is energized, switch means in said second circuit adapted to prepare it for starting the second burner in response to a predetermined 1 second decrement of temperature in the heating medium, a third circuit connected for operation with time delay from the second circuit when the 8 latter is energized, and switch means in the third circuit adapted to prepare it for starting the third burner in response to a predetermined third decrement of temperature in the heating medium.

VERNON S. BECK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 21,569 Crago Sept. 1'7, 1940 1,447,337 Bitgood Mar. 6, 1923 1,811,378 Bannister June 23, 1931 1,918,265 Hartwig July 18, 1933 2,470,996 McGrath May 24, 1949 2,549,952 Wheelock Apr. 24, 1951 

